U.S. Sen. Ron Johnson speaks with reporters in Green Bay ahead of the Wisconsin Republican Party convention in May. Credit: Associated Press

Politicians love sneaking controversial amendments into larger, less problematic bills where they hope they'll simply be overlooked. It's a good strategy for passing a new rule that might otherwise face a real challenge if presented on its own merits. It's not necessarily a great thing for healthy debate and democracy.

Sen. Ron Johnson (R-Wis.) is employing this strategy for his battle to support private schools that receive public money in their quest to be free of pesky public oversight, specifically when it comes to their apparent desire to shrug off the Americans with Disabilities Act.

Last week, Johnson introduced an amendment to the Commerce, Justice and Science Appropriations Act of 2016 that would specifically forbid the Department of Justice from enforcing the ADA for those private schools receiving public funding.

Democratic former Sen. Russ Feingold is going after Republican Sen. Ron Johnson for a $10 million deferred compensation package he received from his Oshkosh-based plastics company, PACUR, shortly before being sworn into the Senate in 2011.

"Six years ago, Ron Johnson sold us a bill of goods," says the narrator of a TV ad set to launch statewide on Tuesday.

The spot plays a clip from a 2010 campaign ad in which Johnson said he was "not a politician."

"But then Sen. Johnson gave himself a $10 million corporate payout, went to Washington and never looked back," the narrator says, then accusing Johnson of voting for tax breaks and trade deals that shipped jobs overseas and trying to weaken protections against Wall Street.

The jab at Johnson's deferred compensation package comes after two ads that show the Republican senator on the floor of PACUR's manufacturing facility, touting his role in starting the company.

Opponents have raised questions about the timing and dollar amount of the $10 million package, since he spent $9 million of his own money on his 2010 campaign.

According to election law experts, as long as an agreement was reached on the deferred compensation package prior to Johnson's campaign, it's aboveboard.

The anti-Johnson spot marks Feingold's sixth ad of the campaign, and one of several going after his opponent directly. Johnson has released two ads, neither of which has mentioned Feingold by name.